Periodontal disease is a bacterially caused by disease. To remove plaque and bacteria, it has been necessary to prescribe chemical drug to patient to subjugate therapeutic unvalue by mechanical scaling.

As a patient on a high dosage of the antibiotics to maintain the effective concentration may produce unfavorable side effects, this decase demands the Slow-release local drug delivery system.

The object of the experiment is to study on the slow-release local drug delivery effects of calcium sulfate compounded with tetracycline that mainly used in periodontal disease.

Experimental groups were divided into four classes as follow:

Group 1 : 10% tetracycline compounded modified calcium sulfate paste.

Group 2 : compounded and hardened 10% tetracycline and calcium sulfate.

Group 3 : compounded 10% tetracycline and calcium sulfate, used just before hardened.

Group 4 : tetracycline-ethylene vinyl acetate fiber.

In the four groups, release concentration, it's durability and the period of absorption by times are observed and concluded as follow:

An effective concentration(4µm/ml) remained until 5 weeks in group 1, 9 days in group 2, 7 days in group 3, 15 days in group 4.

It was fully fused at 11.8 days average in group 2 and 14.8 days average in group 3.

There were no statistically significant results in tetracycline concentration until a week in group 2 and 3(p<0.05)

These results suggest that tetracycline loaded calcium sulfate release sufficient tetracycline and fused in 11~14 days, so calcium sulfate is useful carrier as slow release local drug delivery system